In a silver halide photographic element, a color image is formed when the element is exposed to light and then subjected to color development with a primary aromatic amine developer. Color development results in imagewise reduction of silver halide and production of oxidized developer. Oxidized developer reacts with one or more incorporated dye-forming couplers to form an imagewise distribution of dye. Dye-forming couplers (as well as other various photographic addenda) are typically dispersed in silver halide emulsion layers of the photographic element with the aid of coupler solvents, which are typically oily or low melting compounds.
In any polychromatic chromogenic photographic material, it is desirable that the dyes so formed should have certain properties. For instance, the dyes should be bright in color with very little secondary absorption so that good color reproducibility is obtained. The expectations include resistance to light fade and both humid and dry heat dark fade. The dyes that are formed by any color coupler during processing have a tendency to fade over time as a result of exposure to light, heat, humidity and oxygen resulting in a deterioration of the original recorded image. It is, therefore, highly desirable that the formed dyes should be more resistant towards fading by heat, humidity and light.
Techniques are known in the art for providing resistance to light fade of photographic dyes. Unfortunately, these techniques have not been completely successful resulting in the development of many unique stabilizing chemistries. Compounds which have been disclosed as light stabilizers for yellow image dyes, e.g., include substituted phenolic and blocked phenolic compounds including; heterocyclic phosphorous materials (U.S. Pat. No. 4,749,645), phenolic thiane derivatives (EP 0 310 551), substituted and blocked bisphenols (UK 1,267,287, U.S. Pat. No. 4,782,011, DE 4,307,439, DE 4,307,439, DE 4,320,828, EP 0 508 398, EP 0 538 862, U.S. Pat. No. 5,294,530, U.S. Pat. No. 5,426,021, U.S. Pat. No. 5,441,855, U.S. Pat. No. 5,441,861, U.S. Pat. No. 5,466,569, U.S. Pat. No. 5,891,613, WO 91/008,515, U.S. Pat. No. 5,567,578, U.S. Pat. Nos. 5,284,742, 5,091,294, EP 0 310 552, U.S. Pat. No. 5,935,773). In addition, yellow dyes may also be stabilized against fading by light with the use of thiomorpholine dioxide compounds as described in U.S. Pat. No. 4,933,271,U.S. Pat. No. 5,091,294, U.S. Pat. No. 5,006,665 and U.S. Pat. No. 6,312,881.
Various yellow high boiling coupler solvents have been reported to increase light stability. German patent application DE 1 96 32927 describes the use of cyclic imides, cyclic carbamates, and cyclic ureas as a means of improving the chromogenically developed color image dye stabilities. However, in particular, the amount of dye stabilization to light fade is only modest. U.S. Pat. No. 5,352,572 reports the use of a specific bis-urea compound in combination with malonamide yellow couplers. However, the bis-urea compounds were not shown to be effective for other couplers and were specifically reported to be ineffective for beta-ketoamide yellow couplers. U.S. Pat. No. 6,045,987 describes the use of amide group substituted aromatic compounds, wherein the amide groups are directly bonded to a phenyl ring, as addenda to coupler dispersions, and in particular the use of such compounds in association with magenta and cyan dye image-forming couplers. Essentially equivalent results are reported for the use of such amide group substituted phenyl compounds regardless of whether the amide group substituents comprise normal, cyclic, or branched alkyl groups. U.S. Pat. No. 6,413,707 discloses the use of urethane based coupler solvents and U.S. Pat. No. 6,555,306 describes a substituted dipiperidine compound as a yellow coupler solvent in photographic elements to improve image dye stability. Most recently, U.S. Pat. No. 6,846,620 discloses a class of bis-amide coupler solvents that is relatively low in cost and enhances the light stability and reactivity of the formed yellow dye image.
In spite of past efforts, the coupler solvents and stabilizers developed to date still do not sufficiently improve the light stability of the dye images, especially yellow dye images.